Cephalostachyum pergracile

Cephalostachyum pergracile Munro

Trans. Linn. Soc. 26 : 141 (1868).
2n = 72 (hexaploid)

Origin and geographic distribution
C. pergracile is widespread in the eastern parts of India, in Nepal, in Burma (Myanmar), throughout northern Thailand and in Yunnan Province of China. For map click: Map513.TIF. It is occasionally cultivated there and also outside its natural area (e.g. Hong Kong, Guangzhou in South China Botanic Garden, Lampung (Indonesia), Puerto Rico).

Culms of C. pergracile are widely used in building, (house posts, walling mats, shingles) and as fishing rods. They are easily split into thin strips which are used for basketry. The outer green layer can be split very finely and is used to make handicrafts. The culms are also used as a raw material for paperpulp.
C. pergracile culms are highly esteemed for cooking rice in Burma (Myanmar) and Thailand. Glutinous rice is traditionally cooked in the internode of a 1-year-old culm. Young shoots are edible but have a bitter taste. This bamboo is also recommended as an ornamental because of its glaucous green culms clothed with reddish-brown sheaths.

Production and international trade
In Burma (Myanmar) and Thailand, C. pergracile is used widely and traded locally. No statistics are available.

The fibre dimensions of the culm are: length 2.15-2.80 mm, diameter 16.25-16.46 µm, lumen diameter 3.85-9.33 µm, wall thickness 3.89-6.09 µm; parenchyma content 17.3-18.3%. The culm contains lignin 24-9% and pentosans 18.4%. Average fresh weight of young shoots is 825g before peeling, 168 g after peeling; the edible portion is 20%. The young shoots still taste bitter after cooking. Their canning quality is unsatisfactory.

Tufted, deciduous, sympodial bamboo. Culm erect with pendulous tip, 7-30 m tall, 2.5-7.5 cm in diameter, wall very thin, glaucous green, somewhat whitish puberulous below the nodes; internodes 20-45 cm long; nodes slightly thickened. Branches arising from the higher nodes, many at each node, about equal in size. Culm sheath 10-15 cm x 15-20 cm, thick and leathery, promptly or tardily deciduous, reddish-brown, shiny, usually covered with appressed, blackish, stiff, deciduous hairs toward the base; blade ovate, cordate, cuspidate, 5 cm long, about half as wide as apex of sheath, densely hirsute on adaxial surface; ligule very narrow, 1.5-2 mm long, entire, densely white ciliolate; auricles horizontally extending along the top of the sheath, linear-lanceolate, 3-4 mm wide, densely wavy-bristly along the margins. Leaf blade linear-lanceolate, 10-35 cm x 1.5-6.0 cm, rough on both the surfaces and margins sparsely puberulent beneath; sheath faintly striate, glabrous, ending in a small ciliate callus; ligule very low, entire; auricles usually lacking, leaving 2-3 early caducous, white, long bristles. Inflorescence borne terminally on a leafy or leafless branch, drooping, bearing distant broad heads of pseudospikelets supported by small chaffy bracts; spikelet 1-2 cm long, consisting of 1-2 sterile florets at base, then a fertile floret, ending in a sterile floret or a filiform rachilla. Caryopsis ovoid-cylindrical, about 1 cm long, shiny, ending in a straight beak up to 1 cm long.
Clumps develop very slowly; under favourable conditions they take 12-15 years to produce full-sized culms, while under unfavourable conditions this may take up to 30 years. In a mature clump the ratio of new to old culms is about 1:3. In India, 4 years after planting offsets the clumps had on average 20 culms, 6 m tall and 4 cm in diameter; 6 years after planting, the clumps had 38 culms, 10 m tall and 4.4 cm in diameter.
C. pergracile usually flowers sporadically almost every year. Occasionally it flowers gregariously over extensive areas. Nothing is known about its life cycle. When it flowers sporadically, it generally does not produce viable seed. In 1987 it flowered gregariously in Thailand and the abundance of seed triggered a population explosion of rats. The next season the rats invaded the rice fields, causing severe loss of the crops.

C. pergracile is one of the commonest and most widespread bamboos in mixed deciduous forests of Burma (Myanmar) and Thailand. In the moister forests it co-occurs with Bambusa polymorpha Munro but in the driest forests where Dendrocalamus strictus (Roxb.) Nees is the prevailing bamboo, it is stunted. It is characteristic of low, hilly country, thriving best on well-drained loams and it grows in large stands.

C. pergracile can be propagated by seed, rhizome and culm cuttings. Seedlings are often collected from the forest. Offsets (rhizome parts with roots and 1-1.5 m long parts of 1-2-year-old culms) can be planted directly. Culm cuttings are rarely successful. Only whole culm cuttings gave good results in a trial, 1- and 2-year-old culms produced 3.6 and 4.1 plants per 3 m culm, respectively. In 2-year-old culms the basal parts were best, in 1-year-old culms the middle and top parts were best. Suitable spacing varies according to the purpose of planting. For wind-breaks and fences 3-4 m x 3-4 m is used, for plantations 8 m x 8 m.
Weeding and watering are necessary until the clump is fully established. The application of organic and chemical fertilizer promotes clump and culm development. Natural stands of C. pergracile need to be protected against fire and grazing. Removal of old culms and thinning of congested clumps stimulate the production of good culms. There are no reports of serious diseases. In India, the bamboo hispine beetle (Estigmena chinensis) is the most important pest of standing bamboo; the lesser leaf roller (Pyrausta bambucivora) and the defoliator Pyrausta coclesalis sometimes cause damage. In Thailand, C. pergracile is remarkably resistant to stem borers. Young immature culms are harvested, to be used for cooking sticky rice. For other purposes, mature culms (2 years and older) are harvested. Yield figures are scarce: about 7 t/ha of air-dried culms per year are reported from India and Burma (Myanmar) from a crop with a cutting cycle of 3 years.

Genetic resources and breeding
Although C. pergracile is present in several botanical gardens, no special germplasm collections and no breeding programmes are known for this bamboo.

The prospects for C. pergracile in its natural area are good because of its many uses. Outside this area it may be a promising ornamental. It is recommended to start germplasm collections and to investigate the feasibility of developing faster-growing cultivars.

S. Duriyaprapan and P.C.M. Jansen

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